cargo: bump bitflags from 2.9.0 to 2.9.1 in /src/exercises/bare-metal/rtc in the patch group (#2759)

Bumps the patch group in /src/exercises/bare-metal/rtc with 1 update:
[bitflags](https://github.com/bitflags/bitflags).

Author: dependabot[bot]

src/exercises/bare-metal/rtc/Cargo.lock

@@ -11,7 +11,7 @@ aarch64-paging = { version = "0.9.1", default-features = false }
 aarch64-rt = "0.1.3"
 arm-gic = "0.4.0"
 arm-pl011-uart = "0.3.1"
-bitflags = "2.9.0"
+bitflags = "2.9.1"
 chrono = { version = "0.4.41", default-features = false }
 log = "0.4.27"
 smccc = "0.2.1"